Abstract:

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Stochastic finite element method and reliability technique are used to determine the
safety degree of the turbine blade with parametric uncertainty. The material, geometric parameters
and rotating speed of blade exhibit notable random fluctuations, so the conventional deterministic
analysis of blade can’t provide complete information. The stochastic analysis can tackle the
uncertainties in structural parameters and obtain the probabilistic characteristic of the vibration
characteristic. In this paper, the study focuses on the reliability assessment of the blade with
uncertainty parameters based on the stochastic finite element method (SFEM) and the
mean-variance method. The perturbation stochastic finite element method (PSFEM) is used to
calculate probabilistic characteristic of the natural vibration of the turbine blade. Based on the
stochastic finite element method, the mean-variance method is used to calculate the resonance
reliability of the blade. The example shows that the present method is valid.

Abstract: Forced vibration and liquid corrosion are important reasons for last stage blade failure in
steam turbine. In order to improve reliability of blades in wet steam stages, the dynamic stress and
the liquid-solid impact stress of blade were analyzed firstly, then Neuber’s rule, rainflow counting
method and improved cumulative damage rule were introduced to develop a new model to evaluate
service life of last stage blade. Many factors such as manufacturing quality, metal quality and
operation status were considered, so it is more reasonable for service life assessment of last stage
blade. At last, the service life of a last stage blade of 680mm was analyzed and the result
approximates the practical service life. It is shown the new fatigue model can give some significant
data and is usable for engineering application.

Abstract: As the condition of a certain blade cracked of rotor system of fans, limited short-axletree nonlinear dynamics model is used ,the vibration frequency and nonlinear dynamic stability single-disc rotor is discussed, interior stress distribution and size of rotating shaft after loaded is analyzed concretely by ANSYS software. Through contrast X, Y, X-Y three directions stress distribution of rotating shaft interior, for entity model of near support disc and shaft, it is observed that its field of stress distribution compare dense is near--support field，also stress concentration is relatively bigger after load is added. Meanwhile ANSYS software is used to calculate by simulation this relation of the blade cracking spread width-temporal of four different alloy material and to count the intensity、stress distributing and the axial displacement of the axletree. The best numerical value about elastic modulus and hardness of the material is found by analysis the curve of crackle width- time function.

Abstract: This paper introduces a FEA method for vibration characteristics analysis of an aero-engine shrouded turbine blade and makes an actual modal analysis of this shrouded blade based on this method in UG software environment. The first six natural frequencies and mode shapes of this shrouded blade are calculated. And also, the dynamic characteristics of the shrouded turbine blade are discussed in detail according to the analysis results. The FEA method and the vibration characteristics analysis results in the paper can be used for optimal design and vibration safety verification of this aero-engine shrouded turbine blade.

Abstract: High cycle fatigue of blades caused by forced vibration is an outstanding problem in turbine machines such as turbo engines and ground gas turbines. Dynamical sensitivity analysis (DSA) is put forward and the mathematic model is erected according to blades. DSA on blades includes sensitivity analysis on inherent characteristic (DSAI) and sensitivity analysis on excitation environment (DSAE). The influence laws of dynamical parameters are gained through DSA, and therefore the optimization design on blades is feasible. DSAE is presented by dint of numerical methods, aerodynamic forces in engines possess multifrequency and spatial distributing characteristics, so DSAE on blades is performed against these characteristics and some results are obtained. Finally the resonance criteria are advanced and a new dynamical design method is put forward.

Abstract: Vibration monitoring is widely recognized as an effective tool for the detection and diagnosis of incipient failures of gas turbines. This paper presents a review of vibration based methods for turbine blade faults. Methods typically involved analysis of blade passing frequencies, and extraction of dynamic signals from the measured vibration response. This includes frequency analysis, wavelet analysis, neural networks and fuzzy logic and model based analysis. The literature reviewed showed that vibration could detect most types of blade faults on the basis that dynamic signals are correctly extracted using the most appropriate signal processing method.